Stimulation of Growth and Nucleic Acid Biosynthesis at Low Concentration of Abscisic Acid in Tissue Culture of Spinacia oleracea

The effect of abscisic acid on growth, ultrastructure and nucleic acid biosynthesis was studied in tissue culture of spinach (Spinacia oleracea L.). Low concentration (0.01 mg l^?1) of abscisic acid increased fresh and dry weight of calluses, whereas 1.0 mg l^?1 was inhibitory. The stimulating effect was observed only in the presence of a relatively high concentration of kinetin (1 mg l^?1). The inhibitory effect was partly overcome by the same kinetin concentration. The low concentration of abscisic acid probably accelerated the induction of callus growth after subculture and stimulated cell division in the exponential phase of growth. Electron microscopy showed the presence of numerous polysomes and rough endoplasmic reticulum in callus cells grown at the stimulating abscisic acid concentration. Control cells and cells at the inhibitory concentration had slightly hyaline cytoplasm and were more vacuolated. Incubation of callus tissue with ³²P in the presence of stimulating concentration of abscisic acid showed a significant increase in the rate of biosynthesis of all nucleic acid classes after 8 h, whereas inhibitory concentration produced a decrease in ³²P incorporation. However, when the tissue was grown in the presence of abscisic acid for 20 days, both concentrations decreased the rate of nucleic acid biosynthesis, as compared to the controls.     

Detection of Autoantibodies to Annexin A11 in Different Types of Human Cancer

Introduction  Annexin A11 was previously identified as an autoantigen in 4.1–10.1% of patients with various systemic autoimmune diseases. In this study, an enzyme-linked immunosorbent assay (ELISA) was developed to investigate the occurrence and features of anti-annexin A11 autoantibodies in sera from patients with different types of cancer. Methods  The recombinant protein of GST fused to the N-terminal domain (1–175 residues) of human annexin A11 was expressed and used as antigen in ELISA. A total of 246 serum specimens were analyzed, which includes sera from healthy women (77), patients with ovarian cancer (72), breast cancer (18), colon cancer (19), pancreatic cancer (20), prostate cancer (20), and diabetes (20). Results  The overall titer of anti-annexin A11 autoantibodies in ovarian cancer patients (or primary tumors only) was found much higher than that in healthy controls (P < 0.05). At the cut-off value designating positive reaction, anti-annexin A11 autoantibodies were detected in 12.5% (5/40) of primary ovarian cancer patients with a significant difference from 2.6% (2/77) of the healthy controls (P < 0.05), but only in 6.25% (2/32) of recurrent tumors. ROC curve demonstrated the potential diagnostic value of anti-annexin A11 autoantibodies in primary ovarian cancer patients with an AUC of 0.62 (0.52–0.73). Anti-annexin A11 autoantibodies were also detected in 5.26% (1/19) of colon cancer and 10% (2/20) of diabetes patients but without significant difference from the healthy controls. Conclusion  A convenient assay to detect anti-annexin A11 autoantibodies in patients was developed, and the experimental data are promising but need to be expanded to address their biological/clinical relevance.     

安徽庐江鸭乙型肝炎病毒LJ-76转染细胞系的建立

为建立鸭乙型肝炎病毒ＬＪ－７６的转染细胞系,将ＬＪ－７６病毒ＤＮＡ插入到ｐＵＣ１９的ＥｃｏＲⅠ位点上,分离得到含有双拷贝ＬＪ－７６ＤＮＡ的重组质粒．通过磷酸钙沉淀方法,将经ＣｓＣｌ等密度离心纯化的ＬＪ－７６ＤＮＡ双体导入到人肝癌细胞ＢＥＬ７４０２中．收集转染细胞的培养液进行蔗糖密度梯度离心,所得沉淀经检测发现含有ＬＪ－７６ＤＮＡ并具有特异性ＤＨＢＶ内源性ＤＮＡ多聚酶活性;对上述样品通过ＤｏｔＥＩＡ检测ＤＨＢＶ核心抗原及表面抗原结果为阳性．Ｓｏｕｔｈｅｒｎｂｌｏｔ分析表明转染细胞内存在病毒ＤＮＡ复制中间体ｃｃｃＤＮＡ、ｓｓＤＮＡ和ｒｃＤＮＡ,而ｃｃｃＤＮＡ被认为是复制活动较为活跃的标志．电镜观察转染细胞的上清发现有病毒颗粒的存在．     

Diversity among bacteria isolated from the deep subsurface

Culturable bacteria from the deep subsurface (179 m) at Cerro Negro, New Mexico were isolated and characterized. The average number of viable aerobic bacteria was estimated to be 5×10⁵g^–1 of sediment, but only about 0.1% of these could be recovered on agar medium when incubated under aerobic conditions. Of 158 strains isolated from this depth, 92 were characterized by cellular fatty acid profiles (FAME), 36 by analysis of partial 16S rDNA sequences, and 44 by rep-PCR genome fingerprint analysis using three different sets of oligonucleotide primers (REP, BOX, or ERIC). These analyses showed the majority of isolates (67%) were Gram-positive bacteria and primarily members of genera with a high %G+C DNA. The remaining isolates were -subdivisionProteobacteria (19%) and members of the flavobacteria group (14%). The diversity indices based on these different methods of characterization were very high suggesting this subsurface habitat harbors a highly diverse microbial community.     

Involvement of Cdc42 signaling in apoA-I-induced cholesterol efflux

Cholesterol efflux, an important mechanism by which high density lipoproteins (HDL) protect against atherosclerosis, is initiated by docking of apolipoprotein A-I (apoA-I), a major HDL protein, to specific binding sites followed by activation of ATP-binding cassette transporter A1 (ABCA1) and translocation of cholesterol from intracellular compartments to the exofacial monolayer of the plasma membrane where it is accessible to HDL. In this report, we investigated potential signal transduction pathways that may link apoA-I binding to cholesterol translocation to the plasma membrane and cholesterol efflux. By using pull-down assays we found that apoA-I substantially increased the amount of activated Cdc42, Rac1, and Rho in human fibroblasts. Moreover, apoA-I induced actin polymerization, which is known to be controlled by Rho family G proteins. Inhibition of Cdc42 and Rac1 with Clostridium difficile toxin B inhibited apoA-I-induced cholesterol efflux, whereas inhibition of Rho with Clostridium botulinum C3-exoenzyme exerted opposite effects. Adenoviral expression of a Cdc42(T17N) dominant negative mutant substantially reduced apoA-I-induced cholesterol efflux, whereas dominant negative Rac1(T17N) had no effect. We further found that two downstream effectors of Cdc42/Rac1 signaling, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK), are activated by apoA-I. Pharmacological inhibition of JNK but not p38 MAPK decreased apoA-I-induced cholesterol efflux, whereas anisomycin and hydrogen peroxide, two direct JNK activators, could partially substitute for apoA-I in its ability to induce cholesterol efflux. These results for the first time demonstrate activation of Rho family G proteins and stress kinases by apoA-I and implicate the involvement of Cdc42 and JNK in the apoA-I-induced cholesterol efflux.     

Intracellular calcium buffering capacity in isolated squid axons

Changes in ionized calcium were studied in axons isolated from living squid by measuring absorbance of the Ca binding dye Arsenazo III using multiwavelength differential absorption spectroscopy. Absorption changes measured in situ were calibrated in vitro with media of ionic composition similar to axoplasm containing CaEGTA buffers. Calcium loads of 50-2,500 μmol/kg axoplasm were induced by microinjection, by stimulation in 112 mM Ca seawater, or by soaking in choline saline with 1-10 mM Ca. Over this range of calcium loading of intact axoplasm, the ionized calcium in the axoplasm rose about 0.6 nM/μM load. Similar loading in axons preteated with carbonyl cyanide 4- trifluoromethoxyphenylhydrazone (FCCP) to inhibit the mitochondrial proton gradient increased ionized calcium by 5-7 percent of the imposed load, i.e. 93-95 percent of the calcium load was buffered by a process insensitive to FCCP. This FCCP- insensitive buffer system was not saturated by the largest calcium loads imposed, indicating a capacity of at least several millimolar. Treatment of previously loaded axons with FCCP or apyrase plus cyanide produced rises in ionized calcium which could be correlated with the extent of the load. Analysis of results indicated that, whereas only 6 percent of the endogenous calcium in fresh axons is stored in the FCCP-sensitive (presumably mitochondrial) buffer system, about 30 percent of an imposed exogenous load in the range of 50-2,500 μM is taken up by this system.